Ultrastable and efficient slight-interlayer-displacement 2D Dion-Jacobson perovskite solar cells

Stability has been a long-standing concern for solution-processed perovskite photovoltaics and their practical applications. However, stable perovskite materials for photovoltaic remain insufficient to date. Here we demonstrate a series of ultrastable Dion−Jacobson (DJ) perovskites (1,4-cyclohexanedimethanammonium)(methylammonium)n−1PbnI3n+1 (n ≥ 1) for photovoltaic applications. The scalable technology by blade-coated solar cells for the designed DJ perovskites (nominal n = 5) achieves a maximum stabilized power conversion efficiency (PCE) of 19.11% under an environmental atmosphere. Un-encapsulated cells by blade-coated technology retain 92% of their initial efficiencies for over 4000 hours under ~90% relative humidity (RH) aging conditions. More importantly, these cells also exhibit remarkable thermal (85 °C) and operational stability, which shows negligible efficiency loss after exceeding 5000-hour heat treatment or after operation at maximum power point (MPP) exceeding 6000 hours at 45 °C under a 100 mW cm−2 continuous light illumination.

8. The depth-dependent strain distribution measurement for polycrystalline film mainly provides residual stress from macroscopic film compression or expansion, and does not directly give stress within a single grain or crystal.In Figure 4a and 4b, the peaks largely broaden with increasing ψ.Thus data quality doesn't enough to give the right message, because the strong preferential orientations could affect the result.It is a suggestion that grain size and crystallinity analysis can be utilized to distinguish the differences between the two films.9. Why peak positions of diffractions are different between in-plane and out-of-plane directions in Supplementary Fig. 18. 10.GIXRD and GIWAXS names can be used uniformly in the manuscript.
11.What is wavelength of XRD?It should be revealed in experimental section.
12. The single crystal structure does not seem to explain why CDMA can have good water resistance.
Reviewer #2 (Remarks to the Author): Zhang and coworkers present a study of perovskite solar cells employing a novel large organic cation named CDMA.Such cation, when alone, forms a 2D Dion-Jacobson perovskite structure, while when incorporated in a standard 3D perovskite improves solar cell performance and stability.
Such improvement is attributed to the fact that the large cations may passivate defects at interfaces, grain boundaries and in the bulk.
The strategy of incorporating large cations in perovskite solar cells has been successfully tested in many other studies and is convincingly beneficial.On one side this means that the topic is extremely relevant for the community and timely.On the other hand, the extensive previous use of the same strategy chips at the novelty and thus it is important to understand how the current work stands out.The authors present impressive performances and extensive characterization.However, it seems to me that, at the current stage of perovskite solar cell research, a more in-depth understanding of the effect of the large cations is needed.In particular, I feel several pieces of information provided by the authors do not match to each other and need clarification.In particular, the following points need to be addressed: -Why the efficiency and stability is compared with MAPI and not FAPI or the multi-cation perovskites that offer significant improvements?
-The interpretation of time-resolved PL decays does not seem consistent.The decay time is almost invariably due to trap-assisted recombination, so if it becomes faster, as it does when CDMA is added to the perovskite, it means that trap-assisted recombination becomes faster.The authors claim the opposite.
-Still concerning photophysics interpretation of PL decays: the observed long decay time is most probably not radiative.No physical reason is provided why the initial decay should be to traps, then at long times traps are not effective anymore and only radiative decay is present.This not in accordance to any accepted rate equation or known decay process.In any case, radiative recombination is bimolecular and thus its characteristic time should decrease linearly with increasing excitation fluence.
-Concerning the absorption spectra: why the n=1 DJ perovskite has no exciton peak in absorption?It should display the best-resolved and sharpest exciton peak of the while DJ series.
-Still on absorption spectra: are oscillations related only to the formation of 2D perovskite phases or there is a contribution from intrinsic confinement -see recent work by Laura Herz and coworkers ACS Energy Lett. 2023, 8, 2543−2551.Does the amplitude of the oscillations match the expected fraction of 2D perovskite phases?Does it change with the amount of large cations included?-Concerning the formation of various 2D phases: the authors claim when discussing transient absorption spectra that when CDMA is added only phases with n=3 or larger form, why no trace of n=1 and n=2 phase is detected.How is it possible?Why the various phases do not form according to simple statistics?Other films in different figures show that n=1 and n=2 phases do form with significant abundance.
-Concerning level alignment: if the bandgap energy determined by TAUC plot, what is the effect of the exciton binding energy?Its magnitude is several hundreds of meV, thus it could significantly change the whole picture and could not be neglected at all.Overall, the manuscript showcases notable advancements in performance, and the authors deserve recognition for their thorough characterization efforts.Nonetheless, in order for the manuscript to be considered for publication in Nature Communications, I recommend that the underlying microscopic mechanisms driving the favorable outcomes of the large cations is explained.After undergoing a comprehensive review process, the manuscript could potentially be suitable for publication.

Response Letter to Reviewers
(Text in black: comments and questions of reviewers; Text in blue: our response to reviewers; Text with yellow highlight in manuscript and SI: our revision; Figure R1: figures from Response letter; Supplementary Fig. 1: figures from Supplementary information; Fig. 1: figures from main text; And superscript 1 : references from main text.The "1" here represents for any number.) Reviewer #1 (Remarks to the Author): The main finding of this manuscript is that the CDMA lacking the π−π interactions in comparison with PDMA could provide better stability of the resulting DJ perovskite and higher solar-cell performance.This is an interesting phenomenon and should be studied in depth.However, the current manuscript still contains a lot of unexplained and unclear data that needs to be further clarified.Therefore, I suggest that this article should be major revised before considering acceptance.Some the questions and suggestions below are for reference.
1.The authors used the intensity ratios of I(202)/I(111) from XRD data (Supplementary Figure 17) to define the vertical orientation of 2D inorganic slabs, but the GIWAXS patterns (Figure 2c  In the revised manuscript, we discussed the FWHM of XRD peaks to evaluate the crystallinity of the perovskite films and the orientation of the inorganic perovskite crystals have been explored mainly by GIWAXS patterns.Please see the main text for details : The first paragraph of "Characterization of the Perovskite Films" on page 6 in the revised manuscript.
2. Although the resolution of the images is poor, Figures 2c and 2d seem to show at least four orientations of crystals in the CDMA-based film and three orientations in the PDMA film.The azimuthal distribution of the diffractions in Figure 2c and 2d should be shown in text.It may help to clarify whether or not distribution of the multiple preferential orientations could result in surface hydrophobicity.This is an issue worthy of in-depth study.

✓ Response:
Thanks for the suggestions.We have analyzed the azimuthal distribution of the diffractions [(202) and (111)] in GIWAXS patterns of PDMA and CDMA based films (Figure R1).It is shown that both (111) and (202) diffractions of CDMA film are strong at 45°, and PDMA film shows a strong (111) peak at 90°.The orientations of PDMA and CDMA do exhibit some differences.While about the surface hydrophobicity, we'd like to point out that there is a small (011) peak at around 8.3 °of 1D ( PDMA ) Pb 2 I 6 • 2H 2 O in the XRD pattern of fresh PDMA based perovskite film (please see Figure R2c  3.All (hkl) diffractions in GIWAXS pattern and XRD should be identified in Figure 2c and 2d.A literature report (J.Am.Chem.Soc. 2022, 144, 32, 14897) is for your reference.
6. Water resistant should be more related to the surface structure (see the SEM images in it possible that an arrangement different from that of the crystals forms a hydrophobic layer on the film surface?Some experiments should be tried to directly obtain information about surface structure such as GISAXS measurement with varied titled angles, SEM image of cross-sectional film or depth analysis of X-ray photoelectron spectroscopy (XPS).
✓ Response: Thanks for the reviewer's valuable comments.According to the reviewer's suggestion, we further investigated the cross-sectional scanning electron microscope (SEM).Images of the cross-sectional SEM show no obvious difference between PDMA-and CDMA-based perovskite films (Figure R4).We agree that the water resistant could be related to the surface structure, the orientation of crystals or element distribution et.al., while in this work, we consider that the reaction between PDMA-based perovskites and water molecules could be the dominated reason for the more hydrophilic of PDMA based perovskite films as discussed in question 2. This phenomenon also has been reported in literatures (Adv.Mater.2021, 33, 2105083; J. Am.Chem.Soc. 2015, 137, 7843-7850;et. al.).
8. The depth-dependent strain distribution measurement for polycrystalline film mainly provides residual stress from macroscopic film compression or expansion, and does not directly give stress within a single grain or crystal.In Figure 4a and 4b, the peaks largely broaden with increasing ψ.Thus data quality doesn't enough to give the right message, because the strong preferential orientations could affect the result.It is a suggestion that grain size and crystallinity analysis can be utilized to distinguish the differences between the two films.
✓ Response: Thanks for the reviewer's suggestion.We agree with the reviewer's opinion that the depth-dependent strain distribution measurement for polycrystalline film mainly provides residual stress fro m macroscopic film compression or expansion, and does not directly give stress within a single grain or crystal.It is reported that the release of the residual stress from macroscopic film compression or expansion can lead to better stability under external stimulate (Nat.Commun.2019, 10, 815; Angew. Chem.Int.Ed. 2022, 61, e2022082).We further analyzed the data in Figure 4a and 4b.It shows a slight fluctuation in the Full Width at Half Maximum of the peaks with increasing ψ as shown in Figure R5a , which can lead to reliable results.Besides, another method based on XRD data, Williamson-Hall plots were further applied to calculate the residual strain in perovskite films using Equation:  =  ( 4 ) + /, where β is total broadening of XRD peaks, defined as FWHM, and θ is diffractio n angle, ε is residual strain, K is Scherer constant (≈0.9 for perovskite), λ is wavelength of X-ray (1.5406 Å), and D is crystal size of perovskite film.The detailed linear fitting and data are shown in Figure R5b .
The fit value of the calculated residual strain further shows an almost free residual strain of the CDMA films, consistent with the depth-dependent GIXRD measurements.Also, Figures R5b and R5c are added to Supplementary Information (Supplementary Fig. 21c and Fig. 17b) with brief descriptions, respectively.
9. Why peak positions of diffractions are different between in-plane and out-of-plane directions in Supplementary Fig. 18.
✓ Response: We really appreciate the reviewer's careful review.In the drawing process, we accidentally used the X column of in-plane for drawing the out-of-plane figure.We checked the data and revised them as followed Figure R6 and also shown in Supplementary Fig. 18. 10.GIXRD and GIWAXS names can be used uniformly in the manuscript.
✓ Response: Thanks for the reviewer's suggestion.In this work, GIXRD and GIWAXS are derived from different measurements with different instruments.Depth resolved GIXRD were characterized using a Rigaku Smart Lab X-ray diffractometer at 45 kV and 200 mA, equipped with Cu Kα radiation (λ = 1.54050Å), parallel beam optics and a secondary graphite monochromator.GIWAXS patterns were obtained by using a Xenocs Xeuss SAXS/WAXS beamline system based on an X-ray wavelength of 0.6887Å .
Therefore, we thought it would be better to name them separately to prevent confusion.
11.What is wavelength of XRD?It should be revealed in experimental section.
✓ Response: Thanks for the careful review.The wavelength of XRD is 1.5406Å.We have updated it in experimen t al section in the revised manuscript.
12. The single crystal structure does not seem to explain why CDMA can have good water resistance.
✓ Response: Thanks for the reviewer's valuable comments.DJ types with ditopic diammonium cations are deemed to strengthen the connection between inorganic layers, thereby enhancing stability.Among them, large spacer cations connect adjacent inorganic perovskite slabs via hydrogen bonding, which has been recognized as a key to improving structural stability for water resistance (J.Am.Chem. Soc. 2018, 140, 12226;J. Am. Chem. Soc. 2021, 143, 19901.).Therefore, we extracted the data on hydrogen bonds between space cations and inorganic slabs of n = 1 and n = 2 2D perovskites based on the obtained CDMA and PDMA crystal structures, as shown in Supplementary Fig. 36  molecules. 31In contrast, the relatively strong hydrogen-bond interaction of CDMA cations can strengthen the connection between inorganic layers, thereby resisting the attack of water molecules, protecting the inorganic perovskite layers, and significantly improving stability.
Reviewer #2 (Remarks to the Author): Zhang and coworkers present a study of perovskite solar cells employing a novel large organic cation named CDMA.Such cation, when alone, forms a 2D Dion -Jacobson perovskite structure, while when incorporated in a standard 3D perovskite improves solar cell performance and stability.Such improvement is attributed to the fact that the large cations may passivate defects at interfaces, grain boundaries and in the bulk.The strategy of incorporating large cations in perovskite solar cells has been successfully tested in many other studies and is convincingly beneficial.On one side this means that the topic is extremely relevant for the community and timely.On the other hand, the extensive previous use of the same strategy chips at the novelty and thus it is important to understand how the current work stands out.The authors present impressive performances and extensive characterization.However, it seems to me that, at the current stage of perovskite solar cell research, a more in-depth understanding of the effect of the large cations is needed.In particular, I feel several pieces of information provided by the authors do not match to each other and need clarification.In particular, the following points need to be addressed: 1. Why the efficiency and stability is compared with MAPI and not FAPI or the multi-cation perovskites that offer significant improvements?
✓ Response: We appreciate the positive comments and thank for the valuable suggestions.We found that it is more likely to obtain different n-value 2D perovskites by using MA cations than FA or mixed FA and MA cations in the synthesis of PDMA-and CDMA-based single crystals.Thus, the current work mainly focuses on the synthesis of MA-based 2D perovskites and their application in solar cells.Further work on FA or other multi-cations are going on in the lab and it is expected to get improvement in device performance.
2. The interpretation of time-resolved PL decays does not seem consistent.The decay time is almost invariably due to trap-assisted recombination, so if it becomes faster, as it does when CDMA is added to the perovskite, it means that trap -assisted recombination becomes faster.The authors claim the opposite.This phenomenon is consistent with most reported literature, such as Adv.Funct.Mater.2023, 33, 2212606;Adv. Mater. 2018, 30, 1800710;Energy Environ. Sci., 2020, 13, 3093;etc.3. Still concerning photophysics interpretation of PL decays: the observed long decay time is most probably not radiative.No physical reason is provided why the initial decay should be to traps, then at long times traps are not effective anymore and only radiative decay is present.This not in accordance to any accepted rate equation or known decay process.In any radiative recombination is bimolecular and thus its characteristic time should decrease linearly with increasing excitation fluence.
✓ Response: Thanks a lot for the reviewer's question.The photoluminescence (PL) decays were also applied to study charge extraction kinetics of the 2D perovskite on a substrate with hole transport layer (PTAA).
According to the reviewer's suggestion, we have revised the description on PL decays in the main text and Supplementary information.The details are as follows.
In the revised manuscript page 5 (Last paragraph of Device characteristics in the revised manuscript): Supplementary Fig. 8 shows the PL spectra and decay of DJ perovskites on the PTAA transport layer.
The fit data are summarized in Supplementary Table 4. Remarkable PL quenching is observed on the CDMA-based perovskite film, indicating efficient charge transfer from the active layer to the transport layer.In addition, it is shown that the decay times of CDMA-based perovskite films are smaller than the PDMA, which suggests that the CDMA active layer has a relatively high charge transfer ability from perovskite to PTAA layer. 36,37  In the revised Supplementary information page 44 (Below Supplementary Table 4): The time-resolved photoluminescence decay curves can be fitted by the bi-exponential function: Where A1 and A2 are the relative amplitudes; and τ1 and τ2 are the decay time constants. 57,58  4. Concerning the absorption spectra: why the n=1 DJ perovskite has no exciton peak in absorption?It should display the best-resolved and sharpest exciton peak of the while DJ series.
✓ Response: Thanks for the reviewer's question.The absorption spectra of n=1-3 DJ perovskites are measured based on single-crystal samples, as shown in Supplementary Fig. 13a.In contrast to the films, exciton peaks are smaller in the absorption spectrum of single crystals.An apparent exciton peak of n = 1 can be seen at about 500 nm, as shown in Supplementary Fig. 13a (Figure R7), which is consistent with the absorption of most reported crystal powders (e.g., J. Am.Chem.Soc. 2021, 143, 12063, J. Am. Chem. Soc. 2019, 141, 12880, etc.).We further investigated the absorption spectrum of n =1 film and did find a distinct and sharp exciton peak at about 512 nm.✓ Response: Thanks a lot for the reviewer's question.The amplitude of the oscillations matches the expected fraction of 2D perovskite phases.The ground-state bleaching peaks of these specific wavelengths have been verified and reported by numerous publications, and the 2D phases can be identified by comparing the peak positions in these references (Adv. Mater. 2019, 31, 1901966;Adv. Energy Mater. 2021, 11, 2002733).Besides, the position of these peaks does not change with the change of the amount of cation s, but the intensity changes [e.g., n-Amylammonium, Matter 2021,4, 582-599 (n = 4); ACS Energy Lett.
6. Concerning the formation of various 2D phases: the authors claim when discussing transient absorption spectra that when CDMA is added only phases with n=3 or larger form, why no trace of n=1 and n=2 phase is detected.How is it possible?Why the various phases do not form according to simple statistics?Other films in different figures show that n=1 and n=2 phases do form with significant abundance.
✓ Response: Thank you for your careful review.We have carefully examined and enlarged the TA spectra of CDMAbased films, as shown in Figure R8.It is shown that there is an n = 2 perovskite peak (Figure R8b), but the peak intensity is extraordinarily weak and easy to ignore.According to the reviewer's comment, we According to the reviewer's comment, we also checked all the figures in main text and Supplementary.
In addition to the characterization of pure n = 1 or n = 2 perovskite single crystals (e.g., Supplementary Fig. 13), perovskite films and solar cells fabricated based on the nominal n = 5 precursors can hardly be detected for the features or peaks of n = 1 and n = 2 perovskite phases, such as the UV-vis absorption spectra (Supplementary Fig. 17c).
7. Concerning level alignment: if the bandgap energy determined by TAUC plot, what is the effect of the exciton binding energy?Its magnitude is several hundreds of meV, thus it could significantly change the whole picture and could not be neglected at all.
✓ Response: Thanks a lot for the reviewer's question.We agree with the reviewer about the effect of exciton binding energy on the energy level alignment of 2D perovskites.In this work, the energy diagram was deduced from Tauc plot and UPS measurement.
The exciton binding energy increases with n value and reaches its maximu m at n=1, which could relatively significant enlarge the energy band gap of the perovskites with small n values (Adv.Energy Mater. 2022, 12, 2202333).In this case, it would not change the trend of energy-level alignment in the schematic diagram about charge transfer in the device.
On the other hand, it is very difficult to determine the value of exciton binding energy for perovskite films with different n values since the resulted perovskites (especially with large n values) are composited by mixed phases with different n values in this work.
Thus, we have revised the caption of Supplementary Fig. 16 and noted that the diagram was obtained without considering the exciton binding energy.
Overall, the manuscript showcases notable advancements in performance, and the authors deserve recognition for their thorough characterization efforts.Nonetheless, in order for the manuscript to be considered for publication in Nature Communications, I recommend that the underlying microscopic mechanisms driving the favorable outcomes of the large cations is explained.After undergoing a comprehensive review process, the manuscript could potentially be suitable for publication.
✓ Response: We really appreciate the reviewer's positive comments and valuable suggestions.Accordingly, we further underlined the microscopic mechanism facilitating the favorable outcomes by the large cations.We further measured the size of these two cations, in which the CDMA and PDMA cations show lengths of 7.7 and 7.4 Å, respectively (Fig. 5c).In general, 2D perovskites with longer dimen sional cations have larger layer spacing.However, the slight-interlayer-displacement CDMA perovskites with longer cation lengths show shorter layer spacing, slightly decreasing with the increased layer number of 2D perovskite layers (5.8, 5.5, and 5.3 Å for n = 1-3).The I•••I distance between the inorganic layer for n =1 -3 perovskites are 5. 89,5.63,and 5.48 Å,respectively (Supplementary Fig. 35a).Differently, layer spaces of aligned PDMA perovskites are 6.0 Å (n = 1) and 5.8 Å (n = 2).The schematic diagram to illustrate the difference between the slight-interlayer-displacement and 0-displacement DJ perovskite series is shown in Fig. 5d.Distinctly, decreasing interlayer spaces and tuning their mutual alignment are significant parameters for controlling the optoelectronic and electrostatic properties as they strengthen electronic interactions 29 and strain 41 between the inorganic layers, and consequently, facilitate interlayer charge transport and structural stability.
In addition to the slightly decrease layer distance, we further investigated the microscopic mechanism water molecules. 31In contrast, the relatively strong hydrogen-bond interaction of CDMA cations can strengthen the connection between inorganic layers, thereby resisting the attack of water molecules, protecting the inorganic perovskite layers, and significantly improving stability.

REVIEWER COMMENTS
Reviewer #1 (Remarks to the Author): The revised manuscript still has some unresolved issues and does not provide reasonable solutions.Therefore, I cannot recommend it for publication now.
1.This study should reasonably explain why (CDMA)Pb2I6•H2O is not formed.The current explanation regarding hydrogen bond lengths appears to be a bit of a stretch.The most significant difference between CDMA and PDMA lies in the orientation of the 2D inorganic slabs, as illustrated in Figure R1.Should the authors redefine the correct (hkl) and consider the possibility of a flat-on orientation of the slabs covering the surface leading to hydrophobicity?
3. The authors are unable to define (hkl) correctly, leading to an inability to clarify the orientation relationship between the crystal and the substrate.In the section of Characterization of the perovskite films, the authors mentioned that "In contrast, CDMA-based film shows relatively strong and discrete Bragg spots and out-of-plane distribution….It suggests a high degree of the preferential vertical orientation of the 2D perovskite inorganic frameworks, forming a favorable charge-transport channel in the solar cells."Based on the orthorhombic lattice (Supplementary Table 6), higher intensity of (111) does not indicate the preferential vertical orientation.
4. Figure S18 shows that CDMA has higher intensity of (111) diffraction than that of PDMA at the out-of-plane direction.However, Figure R1 presents a result opposite to those in Figure S18.
7. Some X-ray data use q but some use 2θ, it is recommended to use q uniformly.
Figure 17) to define the vertical orientation of 2D inorganic slabs, but the GIWAXS patterns (Figure 2c and 2d) show multiple preferential orientations of the inorganic perovskite crystals.✓ Response: Thanks a lot for the reviewer's valuable question.Please note, all the mentioned Figure 2c and 2d on the GIWAXS measurements in the questions are mislabeled for the figure number, and they should correspond to Figure 3c and 3d in the main text.
), and this peak becomes prominent when the PDMA based film exposed under relative humidity (RH) of 85-90% for 2 h (please see Fig 4d in the manuscript).This phenomenon originates from that the PDMAbased perovskites easily form a 1D hydrate (PDMA)Pb2I6•2H2O by reacting with water molecules (ACS Energy Lett. 2021, 6, 337-344): 2 ( PDMA ) PbI 4 + 2H 2 O ↔ ( PDMA ) Pb 2 I 6 • 2H 2 O + ( PDMA ) I 2 Contrarily, there are no peak of this hydrate in XRD patterns for both fresh and aged CDMA based perovskite films (please see Figure R2c and Fig 4e in the manuscript).Thus, we consider that the reaction between PDMA-based perovskites and water molecules could be the dominated reason for the more hydrophilic of PDMA based perovskite films.

Figure
Figure R2.a, b, GIWAXS images of the DJ perovskite films.c, XRD image of the DJ perovskite films.

Figure R3 .
Figure R3.The relationship between the instrumental angles .
5. It is difficult to understand what Figure 4d and 4e are trying to express in relation to the residual strain.

Figure
Figure 3a and 3b) than the residual strain inside the crystals.Notably, the preferred orientation of PDMA-and CDMA-based perovskite crystals are different as shown in Figure 2c and 2d.It should be confirmed whether the surface hydrophilicity is changed due to its different orientation of crystals.The current research data of crystalline structures cannot reasonably explain why CDMA-based film can have excellent water resistance.Notably, CDMA without the π−π interactions does not necessarily stack along a single direction.Is

Figure R4 .
Figure R4.Cross-sectional SEM images of the DJ perovskite films.

Figure
Figure R5.a, Linear fit of FWHM-sin 2 φ in the different regions for the PDMA-and CDMA-based film.b, Williamson−Hall plots fitting of DJ perovskite films.c, Comparison of FWHM of the (111)-orient ed XRD peaks.

Figure. R6 .
Figure.R6.Comparison of line-cut profile curves of 2D GIWAXS along in-plane directions and out-ofplane.
Fig.35b), indicating notable twist features and possible seriously affect structural stability.The weak hydrogen-bond interaction and relatively twisted equatorial Pb -I-Pb angles could be the reason that the Thanks for the careful review.In this work, it is worthy to point out that the photoluminescence and timeresolved photoluminescence (TRPL) spectroscopy were applied to study charge extraction kinetics of the 2D perovskite on a substrate with hole transport layer (PTAA).It is different from the method by which TRPL characterization revealed the recombination by directly coating perovskite on a bare glass substrate without transport layer.Remarkable PL and TRPL quenching are observed on the CDMAbased perovskite film, indicating efficient charge transfer from the active layer to the transport layer.
Figure.R8. a, TA spectra under different delay times for the CDMA film under back-photoexcitation. b, Local enlarged view of TA spectrum.
It includes two aspects, which are the I•••I distance between the inorganic layer involved in facilitatin g interlayer charge transport and the N-H•••I hydrogen-bond interaction in relation to structural stability.Details are as follows and also shown in the revised manuscript on page 10 and 11: (Paragraph 2 and 3 of the Structural analyses section in the revised manuscript) Fig. 35b), indicating notable twist features and possible seriously affect structural stability.Based on these, the weak hydrogen-bond interaction and relatively twisted equatorial Pb -I-Pb angles could be the reason that the PDMA-based perovskites easily form a 1D hydrate (PDMA)Pb 2I6•2H2O by reacting with